Not much open sourcey-ness to this, but so cool for us Children of the 80s…a Super Mario Crossover! You can play the original Super Mario Bros. with a twist–as a character from another 80s original NES character. There is Link from Zelda, MegaMan, Simon from the Castlevania games, the dude from Contra, and then Mario. What I LOVE about it though–you have each character’s original weapons, and when you land mushrooms, the weapons get better. Too cool, and a fun way to spend summer vacation!